Automatic telephone system



Feb. 24, 1925.

W. T. POWELL AUTOMATIC TELEPHONE SYSTEM Filed July 1, 1919 ATTORNEY MMOzu m.

Patented Feb. 24, 1925.

UNITED STATES PATENT OFFICE.

WINERED m. POWELL, or ROCHESTER, NEW YOEE, essieNoE To THE srEoNrEEEG-CARLSON TELEPHONE MANUFACTURING COMPANY, or ROCHESTER, NEW YOEK,

A. CORPORATION 0F NEW-YORK.

.AUTOMATIC TELEPHONE S-YSJ'JEILVI,`

Application :tiled July 1, 1919. Serial No. 307,815.

To zZZ whom it may concern Be it known that I, VVINFRED T. POWELL, acitizen of the United States, residing at Rochester', in the county ofMonroe and State of New York, havepinvented certain new and usefulImprovements in Automatic Telephone Systems (Oase 47), of which thefollowing is a full,clear, concise, and exact c lescription.`

This invention relates to telephone systems, and more particularly totelephone systems employing automatic switches in completing Connectionsbetween calling'and called subscribers.

In systems of this character it has formerly been the practice todirectively operate an automatic switch by impulses transmitted from adistant point and then to directively select lthe ywanted line in thegroup previouslyv selected. This method of operation required group andline selecting mechanisms as well as change-over mechanisms, that is,means for disabling the group seletting mechanism while the lineselecting` mechanism is in operation.

One of the features of this invention is the provision of means wherebyan au-tomatic switch may be advanced a distance proportional to thenumber of impulses transmitted in several series.

Another feature of the invention is the provision of means whereby anautomatic switch moves in 'the` same direction inr response to a.plurality of impulses from a distant point, the total number of stepstaken by the automatic switch being equal to the sum of the impulses ofthe various series transmitted.;

Another feature of the invention relates to means for signaling a wantedtelephone line.

An additional feature of the invention is the provision of circuits fortesting a wanted line.

Fig. l of the drawings diagrammatically represents a portion of thetelephone system employing the present invention, and shows a callingllineeXmllidecl through the brushes or Wipers of a numerical Switch te acalled line. The portion of the drawing included within the dottedcircles represcate impulse Senders which may be of any ofthe well knowntypes that have shuntae SpringsL for shuntng the transmitter.

during the transmission of impulses. A push button is provided at eachof the substations to control a break point in aV conductor other thanthe talking conductors that is employed for testing and signaling thewanted line. y

Fig. 2 of the drawings is a front view of the dial of the senderindicating that the sender is arranged to transmit impulses on thedecimal basis in addition tO` other series of impulses, one havingtwelvev impulses in the series and the other twenty impulses. Fig. 3 ofthe drawings is va schematic showing indicating that the switch,represented by the brushes 20, 2l and 22 of Fig. l, has fifty-twoterminals. This view also indicates the various adjustments of dial ofFig. 2 to set the brushes of the swit h in engagement with any ofthedesired lines. V

The switches employed in this system are of the well known rotary t-ype,preferably provided with fifty-two terminals as men-- tioned which arearranged in an arcuate bank for engagement by brushes which areprogressively advanced step-by-step by a ratchet and pawl arrangementand are restored to normal by a well known release magnet. The releasemagnet enployed in connection with the switch may be of any type'whichhas a sluggish armaturel to control the. holding dog'. It should bestated that all of the terminals of the switch are connected to outgoinglines. In the present arrangement the rst terminal of the switchdesignated trunk in Figi 3 is connected to ank outgoing trunk to adistan-t exchange. To select this trunk it is neessary only to removethe receiver from its switchhook whereupon the switch individual to thecalling line will move -to an offV normal position as will be described.The push button is then depressed to signal the distant eX- change. i i

Although a dial sending any number of impulses may be employed inconnection with the present system, it is desirable in the presentarrangement yto employ a sender which sends series of twelve impulses'and twenty impulses inaddition tothe decimal `arramgement ofimpulsingnow in use.

W'ith this brief description of the apparatus employed, it is believedthat the Vpresent inyention will best beunderstood describing the methodof establishing a connection between a calling subscriber at A and acalled subscriber at B. lVhen the calling subscriber at A removes hisreceiverl from its switchhoolr, a stepping relay SR- individual to thisline is energized in a circuit extending from grounded battery, windingor' the relay SR, ring conductor l, primary winding ot the inductioncoil at the substation through the transmitter and impulse spring 2, tipside ot the line 3, winding of the impedance Coil d, to ground. Inresponse to the energization of the stopping relay Slt, the motor magnetMii/i7, is operated over a circuit completed from grounded battery,through its winding, armature and back Contact, inner front contact andarmature or the stepping relay SR, contact ft', ott normal spring ON,lett hand low resistance winding ot the relay 5, to ground. The motormagnet MM is operated in this circuit and causes the numerical switchwhich it controls, to advance one step to an off normal position inwhich it remains until the calling subscriber dials a series ofimpulses.

ln response to t-he first series ot impulses, the stepping relay SRvibrates its armatures once for each impulse transmitted,` and the motormagnet MM is operated in synchronism with the stepping relay SR, over acircuit traceable from grounded battery, winding ot the motor magnet MM,conductor 6, lower-most bach contact and armature of the relay 7,conductor 8, right-hand bac-lr contact and armature of the steppingrelay SR, contact 9 and od normal spring ON, winding of the relay 5, toground. The motor magnet Mhil thus advances its numerical switch onestep in response to each imA pulse transmitted 'from the substation at fThe lower winding of the relay 7 has previously been energized over acircuit completed from grounded battery, lower winding of the relay 7,contact 9 and ott no 1mal spring, winding of relay 5. to ground. rlheenergization of only the lower winding of the relay 7' will not causethis relay to attract its armatures, but will maintain these armaturesin their alternate position whenever attracted.

It will be noted that a circuit for the release magnet REL is closed inparallel with the operating circuit of the motor magnet M'M justdescribed, but since the armature 10 of the release magnet is sluggish,it will notbe attracted during momentary energizations of the releasemagnet and therefore the numerical switch will not be released at thistime.

In response to the next series ot' impulses, if the Wanted substation isdesignated by a two-digit designation, the numerical switch underconsideration will continue to be advanced in the same directionstcp-bystep in 'response to the impulses from the sender at substationA, at the end ot which series the switch will have a number ot stepsequal to the sum of impulses of the two series. It it is necessary todial a third series of impulses, the numerical switch will continue tobe advanced in the same direction as in the case of the preceding seriesot impulses until the terminal ot' the wanted line is reached. Y

lt now becomes necessary to test the want,- ed line to determine whetheror not it is engaged, and if it is notengaged, to apply signalingcurrent to it. These operations are accomplished in the followingmanner. The subscriber at A after having completed the sending ot' thedirective impulsesv` presses the push botton 11, and thereby closes' acircuit from grounded battery, winding of the ringing relay 12, upperwinding el the electrically polarized relay 7, conductor` 13, contactsof the push button 11, contact 14 and shunting spring of the sender,contact 2 of the impulse spring, tip conductor 3 of the line, winding ofthe impedance coil el., to ground, and since the upper winding of therelay 7 is energized in the same direction as the lower winding, thiselectricallj.' polarized relay 7 attracts its armatures.

The relays 7 and 12 are energized in the circuit ust described andattract'their arinatures to apply signaling current to the wanted line.At the lower armature and front contact of the relay 12, a circuit isclosed from ground, over conductor 15, back con-- tact, armature andwinding ot the magnet 1G ot the ringing machine, to grounded battery.The ringing machine thereupon operates to induce an alternating currentin a circuit extending from ground, lamp 17, secondary winding of theinduction coil, lamp 18, conductor 1 9, uppermost' trout con-Y tact andarmature ot the relays 12 and 71 brush of the numerical switch throughthe closed impulse contacts of the sender through the condenser and bellot the substation at B, ring conductor ot the `allcd line, brush 21 ofthe numerical switch` inner-most front contacts and armatures ol relays7 and 12, toground. The relay when energized as described vabove ismaintained energized during conversation through its' lower winding.

Let it be assumed that the wanted subscriber is busy when the brushes20, 21 and 22 ot the numerical switch were placed in engagement with theterminals of this line. Under this assumption a guarding ground will bepresent on the test terminal 23 of the wanted line, which is appliedthrough the low resistance winding ot the relay 5, an ott' normal springand contacty similar' tol 9. a conductor similar to 24 of the othernumerical switch that is in engagement with the wanted line, to the testterminal 23.

Under this condition the upper winding ot lll the electrically polarizedrelay 7 may be energizedtrom this ground` on test terminal 23, testbrush 22, inner-most lower back contact and armature and uppei windingloit the relay '7, conductor 13, push button 1l, contact 14 and shuntingspring ot the sender, the transmitter andY through switchhook contacts,primary ,winding of the induction coil at thesubstation'A.,windingfofthe stepping relay SR, to grounded batter-y. lnthis instance the windings ot the electrically polarized relay areenergized in opposite directions so that this rela-y does not att lactits armatures, and ringing current is not applied to the wantedline. Therelay 12, however,v which is energized whenever the pushbutton 1l isdepressed, closes` a` circuit trom ground, lower armature and frontcontact of relay 12. conductor 15, armature, back contact and right handwinding of relay 5. to; grounded battery. In this circuit the relay 5rapidly vibrates its armatures-thus inducing acurrent which causes atone in the receiver ot the calling subscriber at A in a circuitextending from ground, left hand winding of the relay 5, ott' normalspring andk contact similar to 9, conductor similar to 24 and testterminal 23 of the wanted line at the switch already in engagement withlthis line,test brush 22 of the numerical switchy individual to thecalline line. inner lower back con-tact and upper winding of the relay7, conductor 13, push button 1l, contact 14C, shunting spring of thesender through the condenser and secondary winding of the induction coilat the substation, through the receiver and switchhook contacts, primarywinding of the in-p duction coil, stepping relay SR, to groundedbattery.

Battery is supplied to the calling` party through the windings ofstepping relay Slt and impedance coil 4. Talking battery for the calledsubscriber is supplied through the stepping relay and impedance coilindividual to his line. It should be noted that as soon as the callingsubscriber operated.

the relay 7 in testing the called line, the impedance coil 27 is bridgedacross brushes 2O and 21 to close a circuit for energizing a steppingrelay corresponding to SR, and the motor magnet of the switch individualto called line is operated to cause the switch to advance to an ottnormal position where it. remains during the conversation. TVith thecalled subscribers switch in an off normal position, ground is appliedto the test terminal ot the called line, through the low winding ofrelay 5, to apply a guarding potential to this terminal.-

lVhen the callingsubscriber replaces his receiver on the switchhook atthe close ot the conversation or because the wanted line is busy. the'energizing circuit of the stepping relay SR is interrupted and causesthis relay to retract its armatures. The release magnet REL is nowenergized for a long interval in the circuit previously 'traced fromgrounded battery, winding ot the release magnet, conductor 8, outer backcontact and armature ot the stepping relay SR, Contact 9 and ott' normalspring, ylett hand winding ot the relay 5, to ground. The release magnetin this inst-ance attracts its sluggish armature 10 and thereby releasesthe holding dog et the switch which returns to nor'n'ial position in thewell known manner. The apparatus and circuits are now in condition toroperating on another call.

ln accordance with an additional feature ot the. present system,conference calls,A that is, calls between three or more parties, may beestablished without the intervention of an operator. The conferencecallsare established in the following manner. Each of the conferees thetime when a conference is to be held, removes his receiver from theswitchhook at his substation whereupon the switch individual to his linemoves to its first set of terminals corresponding to those designatedctrunk in Fig. 3. `and he then presses the push button located at hisstation as ir" to signal a wanted party. ln providing` ttor thisarrangement, it is only necessary that the tirst terminals ot theconnector' switches` that is. the terminal designated trunk in Fig.' 3,should not be connected to any outgoing line. The multiple connectionsbetween these first terminals at all the switches are the same as anysubscribers line. ln disestablishinp` the connection it is onlynecessary to have the parties replace their receivers on theswi'tchhooks as is the case oitV an ordinary call.

1. In a telephone system, incoming lines, a plurality ot outgoing lines,automatic switches for interconnecting said incoming` lines with any ofsaid outgoing lines, a test conductor for each ot said outgoing lines,means for applying a busy condition to the test conductor ot a busyline, and a busy signal arranged to be transmitted to an incoming linewhen said line is extended to a busy outgoing line, said busy signalbeing transmitted over a portion of the test conductor or' said busyoutgoing line.

2. In a telephone system, incoming lines, a plurality of outgoing lines,automatic switches for interconnecting` said incoming lines with any ofsaid outgoing lines, a test conductor for each ot said outgoing lines,means for applying` a busy condition to the test conductor of a busyline, and a busy signal arranged to be transmitted to an incoming linewhen said line is extended to a busy outgoing line, said busy signalbeing transmitted over a portion of the test conductor of said busyoutgoing line and a talle ing conductor.

llO

3. In a telephone system, incoming lines, a plurality of outgoing lines,automatic switches for interconnecting said incoming lines with any ofsaid outgoing lines, means for applying a busy condition to the testconductor ot a busy line, and a busy signal arranged to be transmittedto an incoming line when said line is extended to a busy outgoing line,said busy signal being initiated and continued over a portion of thetest conductor of said busy outgoing line.

el. in a telephone system, incoming lines, a plurality oft outgoinglines, automatic switches tor interconnecting said incoming` lines withany of said outgoing lines, means including a manually controlledmechanism for testing said outgoing lines, means for applying a busycondition to the test con` rluctor of a busy line, and a busy signalarranged to be transmitted to an incoming line when said line isextended to a busy outgoing line, said busy signal being initiated bysaid manually controlled means and transmitted over a portion of thetest conductor ot said busy outgoing line.

5. In a telephone system, an incoming line, an impulse transmitterassociated with said line, a plurality of outgoing lines, an automaticswitch, means for receiving several series of impulses and Jforadvancing said switch a distance proportional to the number of impulsesreceived to seize a wanted outgoing line it idle and testing meansincluding an electrically polarized relay for testing said outgoinglines.

6. Ina telephone system, a plurality ot telephone lines, an impulsetransmitter and a progressively movable switch associated with eachtelephone line, means associated with each switch for receiving severalseries -ot impulses from its associated impulse transmitter and foradvancing said switch a distance proportional to the number of im`pulses-received to seize a wanted outgoing line and means responsive tosuch seizure for operating the switch of the wanted outgoing line torender said line unselecta-ble.

7. ln a telephone system, a plurality of telephone lines, an impulsetransmitter and an individual progressively movable switch for eachtelephone line, each of said switches having a normal position, meansassociated with each automatic switch 'for receiving several series ofimpulses and for advancing said switch a distance proportional to thenumber of impulses received to seize a wanted outgoing line and meansresponsive to such seizure and independent of the respense of the wantedparty for advancing the switch individual to the wanted line to anoit-normal position.

8. A telephone system including a sub scribers line, an automaticadding-type connector switch individual to said subscribers linecontrolled over the two sides of the subscribers line in series, asingle row or level ot bank contacts 'for said automatic switch, othersubscribers lines terminating in said bank contacts, subscribercontrolled means for said switch governed over the two tall:- ingconductors of said telephone lines in series for connecting said rstsubscribers line to any one of said other subscribers lines,subscriber-controlled means for ringing the called substation, andautomatic` means for moving said switch to normal position.

In witness whereof, I hereunto subscribe my name this 30th day of J une,A. D. 1919.

`VVIl.\TI*`RED T. POWELL.

